Vulnerability found:
05 December 2007

Vendor informed:
13 December 2007

Severity level:

Richard Brain of ProCheckUp Ltd ( ProCheckUp thanks RSA for being so cooperative and responding so fast.

A remote URI redirection vulnerability affects the RSA Authentication Agent. This issue is due to a failure of the application to properly sanitize URI-supplied data assigned to the 'url' parameter.

An attacker may leverage this issue to carry out convincing phishing attacks against unsuspecting users by causing an arbitrary page to be loaded once a RSA Authentication Agent specially-crafted URL is visited.

Although the 'url' parameter is filtered for protocol URLs such as 'http://' and 'https://', is NOT filtered for other protocols such as FTP or Gopher. An attacker could upload a spoof login page to a FTP server that allows anonymous connections where the victim would be redirected.

Vulnerable server-side program: '/WebID/IISWebAgentIF.dll'

Unfiltered parameter: 'url'


Victim users can be redirected to third-party sites for the purpose of exploiting browser vulnerabilities or performing phishing attacks.




the redirect will only take place in browsers which consider URLs with only one slash after the colon symbol ':' as valid when performing redirects - i.e.: "Location: ftp:/"

Successfully tested on

RSA Authentication Agent for Web for Internet Information Services in conjunction with Mozilla Firefox

Proof of concept:
Example of specially-crafted URL:



GET /WebID/IISWebAgentIF.dll?Redirect?url= HTTP/1.1
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.0; en-GB; rv: Gecko/20071127 Firefox/
Accept: text/xml,application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5
Accept-Language: en-gb,en;q=0.5
Accept-Encoding: gzip,deflate
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7
Keep-Alive: 300
Connection: keep-alive


HTTP/1.x 302 Object Moved
Connection: Keep-Alive
Content-Length: 194
Date: Tue, 18 Dec 2007 09:35:19 GMT
Location: ftp:/
Content-Type: text/html
Server: Microsoft-IIS/6.0
X-Powered-By: ASP.NET

How to fix:
The vendor has stated that this issue was addressed in the RSA Authentication Agent RSA customers can download the upgrade from the RSA web site.


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